Am i pregnant or not??PLEASE HELP

Hi girls

So my period is regular meaning it last for 7 days . Ive been trying to concieve. So i had unprotected sex on my fertile days for the month of december and My period was normal for december. My next period was suppose to be on the 1st of january. It did came but it last for 2 days and it wasnt heavy how it normally comes. Some people said it would be implantation blood but im not sure what is that So im worried . What can it means? Please help please....